Comparison of element accumulation of different moss- and lichen-bags, exposed in the city of Sofia (Bulgaria)

The levels of elements (Al, As, Au, Ba, Br, Ca, Cd, Ce, Cl, Co, Cr, Cs, Cu, Fe, Gd, Hf, I, K, La, Mg, Mo, Mn, Na, Ni, Rb, Sb, Sc, Se, Sm, Sr, Ta, Ti, Tb, Th, U, V, Zn, Zr, W) in the exposed and unexposed mosses and lichens were determined by INAA. Two moss species (Sphagnum girgensohnii and Hypnum cupressiforme) and two lichen species (Pseudevernia furfuracea and Usnea barbata) were exposed in bags in three sites of the city of Sofia from October, 2001 to January, 2002. In order to evaluate and compare the accumulation of diverse elements by the four biomonitors and to assess the accumulation in three different locations of the urban area, ANOVA analysis tool was used. The Hypnum cupressiforme was proved to be less suitable for active monitoring with bags than the rest of investigated biomonitors. In spite of the fact that the material used for transplant should be unpolluted one, a less initial element concentration in unexposed biomonitor is not a sufficient condition for obtaining a higher relative accumulation factor.